In rotatable and, in particular, rotary driven shafts, deformations and, in particular, shaft deflections may occur during operation (i.e. when rotating the shaft), if there are forces not acting in parallel with (e.g. perpendicular to or at an angle to) the longitudinal axis of the shaft.
The following cases may be distinguished, namely cases in which the direction of forces not acting in parallel with the longitudinal axis of the shaft remains substantially the same, and cases in which the direction of forces not acting in parallel with the longitudinal axis of the shaft changes and, in particular, rotational radial forces occur.
In the first case, a substantially stationary shaft deformation or shaft deflection occurs. This may be referred to as rotational deformation or rotational deflection (or bending).
In the second case, a shaft deformation or shaft deflection occurs, the characteristic or direction of which changes as a function of the change in direction of the underlying forces. This is the case, in particular, with rotational radial forces. This may then be referred to—following the term “rotational radial forces”—as rotational shaft deformation or shaft deflection.
Examples of the first case include paper machines and rope winches, wherein the direction of forces not acting in parallel with the longitudinal axis of the shaft does not change (e.g. forces due to cooperating paper rollers arranged on shafts; forces acting on a rope arranged on a rope winch).
Examples of the second case include oscillators and vibrators, wherein unbalanced masses are provided on shafts which are rotated together with the shaft thereby generating rotational radially acting forces with respect to the longitudinal axis of the shaft or axis of rotation.
For compensation of rotational deformation or rotational deflection (or bending) in the first case, it is known, for example, to provide the radially outward part of a shaft bearing (e.g. an outer roller bearing ring) with a hinge bearing providing a hinged connection, for example, to a housing. However, such approaches are not suitable or only suitable to a limited degree for providing for compensation in the second case (rotational shaft deformation or shaft deflection).